1. Field of the Invention
Embodiments of the present invention relate generally to optical communication systems and components and, more particularly, to a multicast optical switch.
2. Description of the Related Art
Optical switches are widely deployed in optical communication networks to provide functions such as optical signal routing, protection switching, and system performance monitoring. In particular, multicast optical switches, which are capable of delivering a copy of a single optical signal to multiple destinations simultaneously, have been identified as a key component for multiplexing and routing different optical signals into or out of a single optical fiber. This capability is especially useful for Colorless Contentionless and Directionless Reconfigurable Optical Add-Drop Multiplexers (ROADMs) used in wavelength-division multiplexing (WDM) systems. For a full description of how multicast switches enable next-gen CDC-ROADMs see, for example, “Next-generation ROADM technologies and architecture”, Paper 8283-8, SPIE Photonics West 2012 Conference 8283.
Multicast optical switches using planar lightwave circuit (PLC) switches and splitters are known in the art, but suffer from various drawbacks. When such multicast switches are configured with discrete PLC splitters and switches, these optical components are typically interconnected by fiber pigtails, resulting in high cost and unwanted manufacturing complexity due to the larger number of fiber interconnections required. For example, to assemble an 8×16 multicast switch constructed from a plurality of individual PLC splitters requires sixteen 8×1 PLC splitters, eight 16×1 PLC splitters, and 128 fiber pigtail connections spliced therebetween. Alternatively, the various splitters and switches of a multicast optical switch can be integrated into a single monolithic PLC, but such configurations are generally high cost, difficult to fabricate, and suffer from low manufacturing yield.